Preparation and properties of LiCo Mn Ni1−−O2 as a cathode for lithium ion batteries

Abstract The preparation of LiCoyMnxNi1−x−yO2 from LiOH·H2O, Ni(OH)2 and γ-MnOOH in air was studied in detail. Single-phase LiCoyMnxNi1−x−yO2 (0≦y≦0.3 and x=0.2) is obtained by heating at 830–900°C. The optimum heating temperatures are 850°C for y=0–0.1 and 900°C for y=0.2–0.3. Excess lithium (1≦z≦1.11 for y=0.2) and the Co doping level (0.05≦y≦0.2) do not significantly affect the discharge capacity of LizCoyMn0.2Ni0.8−yO2. The doping of Co into LiMn0.2Ni0.8O2 accelerates the oxidation of the transition metal ion, and suppresses partial cation mixing. Since the valence of the manganese ion in LiMn0.2Ni0.8O2 is determined to be 4, the formation of a solid solution between LiCoyNi1−yO2 and Li2MnO3 is confirmed.